1. Field of the Invention
This invention relates in general to electrical terminal blocks and more particularly to an arrangement and method for locking an insulated electrical conductor to a terminal block employing slot-type terminal contacts.
2. Description of the Prior Art
Terminal blocks employing electrical terminal contacts, are used in great variety and numbers in communication and other data handling systems to facilitate electrical connection of individual solid or stranded insulated electrical conductors or wire to external circuits or other conductors. In the past, the electrical connection has been accomplished by stripping the insulation from the end of the conductor and then soldering the conductor to the terminal contacts. This procedure requires considerable skill on the part of workmen making the solder connection. In miniaturized terminals particularly, there is also a tendency for the solder to bridge adjacent contacts producing undesired circuit connections. These disadvantages, have been overcome to some extent by terminal blocks that employ insulation-penetrating clip-type, or slot-type terminal contacts.
A typical slot-type contact is shown in U.S. Pat. No. 3,239,796 to S. N. Buchanan, et al, issued Mar. 8, 1966. The terminal contact includes a pair of electrically conductive vertical blades joined at one end and free at the other. The free ends are spaced apart a distance less than the diameter of the conductor. Moreover, the construction of the blades permit penetration of the insulative material to tightly bite into the conductive portion of the electrical conductor. The penetration of the insulation is obtained by compressive forces applied to the conductor during seating of the wire in the terminal contact slot by the contact blades and a precision tool. Problems may arise with this slot-type terminal in that, with the use of smaller diameter wire (24 WGS or greater) the clamping action of the slot and blades to the conductor material is delicate and the wire must be restrained from flexing at this point so as not to damage the conductor. The flexing may cause degradation of the conductor material which ultimately results in the conductor breaking off at the terminal contact.
Accordingly, it is an object of the present invention to provide a simple, effective, arrangement and method for locking an insulated electrical conductor to a terminal block employing slot-type terminal contacts.
Additionally, it is a further object of the invention to provide a locking arrangement that may be formed from the terminal base material without additional loose parts.